April 1996 - August 2000
Otto-von-Guericke University of Magdeburg, Germany
Postdoctoral Researcher (C1) at the Institute for Simulation and Graphics
Head of Institute: Professor Thomas Strothotte

Research

I am interested in computer graphics and visualization. In the last years I especially focused on the following fields: modeling and visualization of complex objects (modeling and simulation of botanic and landscapes), sampling and rendering foundations, non-photorealistic rendering techniques, and information visualization.

Modeling and visualization of complex objects: many applications in urban and environmental planning, in architecture, landscaping, ecology, arts, film and advertisement need complex objects and scenes for various types of visualizations. We found efficient algorithms for the creation, level-of-detail modeling and display of scenes with billions of surfaces. Our work concentrated on botanic objects (trees, landscapes). Already in 1996 I founded the companies Greenworks Organic Software (www.greenworks.de) and later Xfrog, Inc. (www.xfrog.com) to develop programs for plant modeling. One product is the well-known xfrog modeling software, which is used widely and was involved in many movie productions such as Avatar. Together with the Chinese Academy of Sciences we developed a completely new method to represent scanned tree objects, thus enabling data-driven models to be shown efficiently in computer graphics scenes.

Sampling and rendering foundations: Sampling is one of the basic problems of computer graphics. Good sampling strategies allow producing images with reduced or special kinds of noise. For many years it was not clear what characterizes good sampling sets. We developed various methods to produce such sets and finally found a mathematical description using Henkel transforms that allows characterizing and tuning such sets optimally.

Non-photorealistic rendering techniques: these techniques aim at creating abstract visual representations for various applications in simulation, visualization, film and arts. In contrast to the traditional rendering paradigm of creating images that are indistinguishable from photographs, non-photorealistic (abstract) rendering allows to vary geometric details, alter shading styles and modify the geometric representation within a single image. The attention of the viewer can be directed to intended parts, representational styles can help her/him understanding relations between objects, to distinguish between existing and planned objects and much more. Dealing with such rendering techniques allows medical and psychological researchers furthermore to explore and understand the working of our visual system.

Information visualization: This area tries to encode various kinds of information visually in the form of computer images. Such encodings help to visually explore complex data and are used in combination with data mining techniques. In particular we worked in software visualization to structurally evaluate very large software systems, in visualization for Biology and Chemistry and text visualization. The latter one might sound strange since text itself is a visualization. However, large amounts of text such as software systems of large text corpora tend to get invisible since they cannot be comprehended by reading any more. Visualization techniques allow assessing such corpora, the linguistic analysis enables systems to detect important themes and topics.